Instrument eor taking altitude oe the sun



F. YEISER. Altitude Instrument Patnted Feb. 8, 1859.

N. PETERS. hala-Lilhcgmpher. Wnhingmn. D. c.

UNITED sra rarnnr ornron.

FREDERICK YEISER, OF LEXINGTON, KENTUCKY.

rnsrnunnn'r FOR TA G ALTITUDE on THE sun.

Specification of Letters Patent No.

the same.

Similar letters of reference in the two figures indicate corresponding parts.

This invention consists in determining the plane of the meridian at any time in the forenoon or in the afternoon, by means of a spirally slotted cylinder which is attached to a horizontal rotary frame in such a relation to a vertical pin and to a line which is strongly defined on the upper surface of the frame and which is provided with a toothed sector which gears into cogs on the top of a stationary disk, in such a manner that when this cylinderis placed in such a position that the ray of the sun passes through the inner end of the spiral slot, and when the frame is now slowly rotated on its axis, the ray of the sun ceases to pass through said spiral slot at that moment when the plane which is determined by the above named vertical pin and by the strongly defined line on the upper surface of the rotary frame coincides with the plane of the meridian.

To enable others skilled in the art to fully understand and construct my instrument, I will proceed to describe it.

The moving parts of the instrument rest on a circular plate A, of metal or other suitable material, having an upright shaft B, permanently fixed in its center, to the upper end of which is secured a horizontal circular plate or disk C, from the center of which rises a vertical wire rod D, and astrongly defined line, 1, 2, is made over the surface of the disk C, radially from its center to its periphery. On the top of the base plate A, and between it and the disk C, is arranged a rectangular frame E, consisting of two parallel horizontal bars E, E, through an opening in the center of which the upright shaft B, loosely passes, and which are connected together at their ends by blocks E in such a manner as to enable said frame to freely traverse around said upright shaft.

22,913, dated February 8, 1859.

the side of the frame, is drawn a black or otherwise strongly defined line, 3, 4:, similar in every respect to the radial line 1, 2, on the surface of the disk C.

To the upper end of the vertical standard F, is jointed by a horizontal screw rod or bolt, upon which it turns, ablock or hub H, on the face of which is secured the toothed sector I, which gears into a series of pins or cogs J, which are attached to the upper surface of the disk C, and which extend segmentally a little more than one-quarter of its circumference.

The block or hub H, is provided with a shaft H, which extends radially from one end of the same, and it fits exactly into an opening in the inner or lower end of a cylinder L, provided with a clamp screw M, which presses against the shaft H. The cylinder L, is bisected by a spiral slot K, which extends nearly from one end of the cylinder to the other, and which forms part of a turn of a right handed screw thread, the pitch of which would be about double the length of the cylinder. This slit divides the cylinder in two parts of exactly the same size, so that whenever a transverse section of the cylinder at right angles to its axis is taken, the slit appears in a straight line passing through the center of said section,

as represented in Fig. 1, in black and in Fig. 2, in red outline.

The operation is as follows. The instrument is first leveled and turned until the shadow of pin D, covers the line 1, 2, and the cylinder L, is brought into a horizontal position and turned until the ray of the sun passes through that portion of the slit K, which is nearest to the end of the hub H, and inthis position the cylinder L, is fastened by means of the set screw M. If now the frame E, be slowly rotated in the direction in which the sun travels (the Whole operation must be accomplished, of course in such a space of time that the yearly motion of the earth has no influence on the observation) the cylinder L, which is rigidly attached to the frame E, begins to move with this frame around the center B, and at the same time it begins to rise by the action of the toothed sector I, and the cogs J, on the disk C, and the ray of the sun will cease to pass through the slit K, just at that moment, when the plane passing through the pin G, and the line 3, 4, coincides With the meridian, and if the instrument be left in this position, the shadow of the pin G, will cover the line 3, 4, at the moment the sun passes through the meridian. It will be noticed, that the distance over which the frame E, has to be moved depends upon the azimuth of the sun at the time of the observation, and the distance to which the cylinder L, rises, by this rotating motion, upon the corresponding altitude of the sun. Suppose it be 9 oclock a. m., then the sun has to travel over an arc of 45 degress in the parallel circle in which it appears to move at the time of the observation, in order to come into the plane of the meridian, and as the axis of the cylinder L, is at right angles with the edge of the frame E, and with the line 3, 4, it will be necessary in order to get the ray of the sun to pass through the inner portion of the slit K, to turn the base-plate A, to such a position that the plane passing through the line 3, 4, and through the pin G, makes an angle with the plane of the meridian which is expressed by the azimuth of the sun at the time of the ob servation. If the frame E, be now turned in the direction in which the sun travels, the cylinder L, will be brought in such a position that the ray of the sun can not pass any more through the slit K, as soon as the frame has been turned over an are equal to the azimuth of the sun at the time of the observation, and the plane passing through the pin G, and through the line 3, 4, Will coincide with the plane of the meridian at the moment in which the ray of the sun ceases to pass through the slit K.

It is obvious that an observation may be taken at any time in the forenoon, and the time when the sun passes through the meridian may be thus determined, if the instrument is brought to such a position that the plane G, 3, 4, coincides with the plane of the meridian, as in this case the shadow of the pin Gr, covers the line 3, 4, at the moment in whi h the sun enters the meridian.

In order to make the instrument available for observations in the afternoon, it is necessary to arrange the slit K, in such a .manner that it forms a part of a left-handed screw thread, all other parts being exactly the same, and an observation may then be taken at any time in the afternoon in the same manner which has been described.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is-

1. The arrangement of the spirally slotted cylinder L, on a rotary frame E, in such relation to a pin G, and to a strongly defined line 3, 4, that it operates substantially as and for the purposes specified.

2. And, in combination with the rotary frame E, I also claim operating the cylinder L, by means of a toothed sector I, which gears into cogs J, which are attached to the stationary disk C, in the manner and for the purpose substantially as described.

FREDERICK YEISER. lVitnesses:

BERRY F. GRAVES, Z. GIBBoNs. 

